Time Charts

Introduction

Time charts show value changes over a time. There are currently three ways to show time series in Davisor Chart:

• scatter charts - Maps <time, value> pairs into plot area with or without connecting lines.
• line chart with time labels - Shows equally spaced data points with time formatted labels.
• line chart with time series - Maps values into listed positions in linear time axis.

Data Model

Mandatory channels:

• Scatter Chart: two grouped value channels
• Time Series Line Chart: time and one or more value channels
• Line Chart: label and one or more value channels

Optional channels: paint, color, url, alt.

Scatter Chart

In scatter chart, either of the x- and y-axis can be time valued. Data series are represented as groups of two value columns having the same number of entries. There can be several data series with any number of data points in each as long as x- and y-axis data types are the same for all series.

Line Chart

In line chart the time stamps are common for all the values. If the data values are wanted to map into linear time axis, then the time stamps must be given in a time channel. If the time stamps are just informal, then they can be given in label channel. In the latter case the data points are equally spaced into the plot area in the order they are represented in the data. In both cases the X-axis labels can be formatted using the time formats.

Which Method I Should to Use?

The optimal time series representation method depends on the data you have:

• If your data is summarized over some time category, use line chart with label channel. For example, if you have sales numbers per month, use label channel with month names.
• If you have several data values for the same dates or time stamps, it is often easiest to use line chart with time channel. See the example in CSV DataSource page.
• If you have <time, value> pairs, use scatter chart.

Examples

Two series line time chart with shared but irregular steps.

Show XML Edit Chart

Two series scatter time chart with distinct irregular steps.

Show XML Edit Chart

Line chart with non-linear time axis.

Show XML Edit Chart

Notes

It is left to the user to sort the data when needed. For example, the sort data source can be used. The data points are rendered in the order they come in, so scatter chart and time series line chart will draw lines backwards when necessary. "Ordinary" line chart doesn't care about label contents, but just draws the labels as they are.

Channel type "time" is just an alias for "position" channel type. It can be used to map any kind of data (not only dates and time stamps but integers and floats as well) to x-axis.